1. Field of the Invention
The present invention relates to a torque sensor and a ferro-magnetic foil therefore, and a method for manufacturing such a torque sensor.
2. Description of the Prior Art
Torque sensors are known, for example, as described in IEEE Transactions On Magnetics, Vol. Mag. 20, September 1984, pages 942-947 and 951-953, having a strip of magnetostrictive amorphous material firmly secured to the circumference of a rotatable shaft, surrounded by primary and secondary electrical windings. The strips of amorphous material are glued to the circumference of the shaft spaced from each other and disposed at an angle of 45.degree. relative to the axis of rotation of the shaft. The shaft is concentrically surrounded by an excitation coil an two secondary coils. The voltages generated in the secondary coils can be compared and evaluated, for example, in a bridge circuit. A signal substantially proportional to the torque acting on the shaft is thus obtained. This signal is dependent on the torque because the torque deforms the shafts, and the strips attached thereto, and the magnetic properties of the ferro-magnetic material comprising the strips is changed when the strips are subjected to a mechanical stress.